Currently learning Italian, I’ve been looking for ways to convert Italian easy-reader books into PDF and then Word format so I can segment the text and quietly work on them with my CAT tool (a little premature I agree); however, this seems impossible in Kindle, unless you open Kindle on your PC and cut-and-paste piecemeal, i.e. page-by-page, which takes aeons. Fortunately I found this article – Convert a Kindle ebook to a different format – which explains how to use a tool called Calibre to save the books on your PC in a different format, be that Epub, MOBIl, PDF etc. Once saved, the books can be converted into a format which can be opened in PDF and then Word, and then you can work on them at leisure. It’s also a useful backup in the event that your Kindle account ever goes awry. Hope this helps.
Source:
http://thecyclingtranslator.com/2013/05/25/saving-kindle-e-books-to-your-pc/